Teen Exposure to THC May Weaken Immune System Later in Life

Using marijuana as a teen can do serious long-term damage to the immune system, said a team of Italian scientists.

The new research, published in the October 2014 issue of the Journal of Leukocyte Biology, suggests that exposure to THC, the active ingredient in marijuana, during the teen years can cause autoimmune and chronic inflammatory diseases such as multiple sclerosis, inflammatory bowel disease and rheumatoid arthritis as an adult.

Scientists injected adolescent mice — or mice the equivalent age of about 12-18 in human years —with THC for ten days. Another group of adolescent mice were given a placebo. At the end of the treatments, both groups were left undisturbed for about two months, until they reached adulthood. Their immune system activity was then looked at, taking into consideration several measurements, such as the ability of the body to produce antibody response to vaccination.

The study found that the group of mice given THC had severe alterations of immune responses as adults.

“I hope that the knowledge that early exposure to marijuana is associated with immediate and long-term deleterious effects on the immune system may reach adolescents and their families,” said Paola Sacerdote, Ph.D., a researcher involved in the work from the Università degli Studi di Milano in Milano, Italy. “The increased risk of getting sick in adulthood may hopefully be a deterrent for marijuana abuse among young individuals.”

John Wherry, Ph.D., Deputy Editor of the Journal of Leukocyte Biology, added, “The immune system is characterized by an impressive ability to ‘remember’ previous exposures and changes during the period of immune system development especially early in life can have important long-term consequences,” he said. “These studies not only point to adolescence as a key phase of immune system sensitivity, but also highly the dramatic and long-lasting negative effects that a common recreational drug abused by teenagers may have on immune function.”